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Dive into the research topics where Homero Rivas is active.

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Featured researches published by Homero Rivas.


Surgical Endoscopy and Other Interventional Techniques | 2010

Consensus statement of the consortium for laparoendoscopic single-site surgery

Inderbir S. Gill; Arnold P. Advincula; Monish Aron; Jeffrey Caddedu; David Canes; Paul G. Curcillo; Mihir M. Desai; John C. Evanko; T. Falcone; Victor W. Fazio; Matthew T. Gettman; Andrew A. Gumbs; Georges Pascal Haber; Jihad H. Kaouk; Fernando J. Kim; Stephanie A. King; Jeffrey L. Ponsky; Feza H. Remzi; Homero Rivas; Alexander S. Rosemurgy; Sharona B. Ross; Philip R. Schauer; Rene Sotelo; Jose Speranza; John F. Sweeney; Julio Teixeira

Inderbir S. Gill • Arnold P. Advincula • Monish Aron • Jeffrey Caddedu • David Canes • Paul G. Curcillo II • Mihir M. Desai • John C. Evanko • Tomasso Falcone • Victor Fazio • Matthew Gettman • Andrew A. Gumbs • Georges-Pascal Haber • Jihad H. Kaouk • Fernando Kim • Stephanie A. King • Jeffrey Ponsky • Feza Remzi • Homero Rivas • Alexander Rosemurgy • Sharona Ross • Philip Schauer • Rene Sotelo • Jose Speranza • John Sweeney • Julio Teixeira


Surgical Endoscopy and Other Interventional Techniques | 2010

Single-incision laparoscopic cholecystectomy: initial evaluation of a large series of patients.

Homero Rivas; Esteban Varela; Daniel J. Scott

BackgroundFindings have shown that single-incision laparoscopic cholecystectomy (SILC) is feasible and reproducible. The authors have pioneered a two-trocar SILC technique at the University of Texas Southwestern. Their results for 100 patients are presented.MethodsFrom January 2008 to March 2009, 100 patients with symptomatic gallbladder disease underwent SILC through a 1.5- to 2-cm umbilical incision using a two-port (5-mm) technique. For nearly all the patients, a 30° angled scope was used. The gallbladder was retracted, with two or three sutures placed along the gallbladder. These sutures were either fixated internally or placed through the abdominal wall to obtain a critical view of Calot’s triangle. The SILC procedure was performed using standard technique with 5-mm reticulating or conventional laparoscopic instruments. The cystic duct and artery were well visualized, clipped, and divided. Cholecystectomy was completed with electrocautery, and the specimen was retrieved through the umbilical incision.ResultsIn this series, 80 women (85%) and 15 men (15%) with an average age of 33.8 years (range, 17–66 years) underwent SILC. Their mean BMI was 29.8 kg/m2 (range, 17–42.5 kg/m2), and 39% of these patients had undergone previous abdominal surgery. The mean operative time was 50.8 min (range, 23–120 min). The mean estimated blood loss was 22.3 ml (range, 5–125 ml), and 5% of the patients had an intraoperative cholangiogram. There were no conversions of the SILC technique. A two-trocar technique was feasible for 87% of the patients. For the remaining patients, either a three-channel port or three individual trocars were required. A SILC technique was used for 5% of the patients to manage acute cholecystitis or gallstone pancreatitis.ConclusionThe SILC technique with a two-trocar technique is safe, feasible, and reproducible. The operating times are reasonable and can be lessened with experience. Even complex cases can be managed with this technique. Excellent exposure of the critical view was obtained in all cases. The SILC procedure is becoming the standard of care for most of the authors’ elective patients with gallbladder disease. Clinical trials are warranted before the SILC technique is adopted universally.


Arteriosclerosis, Thrombosis, and Vascular Biology | 2014

T-Cell Profile in Adipose Tissue Is Associated With Insulin Resistance and Systemic Inflammation in Humans

Tracey McLaughlin; Li-Fen Liu; Cindy Lamendola; Lei Shen; John M. Morton; Homero Rivas; Daniel Winer; Lorna L. Tolentino; Okmi Choi; Hong Zhang; Melissa Hui Yen Chng; Edgar G. Engleman

Objective— The biological mechanisms linking obesity to insulin resistance have not been fully elucidated. We have shown that insulin resistance or glucose intolerance in diet-induced obese mice is related to a shift in the ratio of pro- and anti-inflammatory T cells in adipose tissue. We sought to test the hypothesis that the balance of T-cell phenotypes would be similarly related to insulin resistance in human obesity. Approach and Results— Healthy overweight or obese human subjects underwent adipose-tissue biopsies and quantification of insulin-mediated glucose disposal by the modified insulin suppression test. T-cell subsets were quantified by flow cytometry in visceral (VAT) and subcutaneous adipose tissue (SAT). Results showed that CD4 and CD8 T cells infiltrate both depots, with proinflammatory T-helper (Th)-1, Th17, and CD8 T cells, significantly more frequent in VAT as compared with SAT. T-cell profiles in SAT and VAT correlated significantly with one another and with peripheral blood. Th1 frequency in SAT and VAT correlated directly, whereas Th2 frequency in VAT correlated inversely, with plasma high-sensitivity C-reactive protein concentrations. Th2 in both depots and peripheral blood was inversely associated with systemic insulin resistance. Furthermore, Th1 in SAT correlated with plasma interleukin-6. Relative expression of associated cytokines, measured by real-time polymerase chain reaction, reflected flow cytometry results. Most notably, adipose tissue expression of anti-inflammatory interleukin-10 was inversely associated with insulin resistance. Conclusions— CD4 and CD8 T cells populate human adipose tissue and the relative frequency of Th1 and Th2 are highly associated with systemic inflammation and insulin resistance. These findings point to the adaptive immune system as a potential mediator between obesity and insulin resistance or inflammation. Identification of antigenic stimuli in adipose tissue may yield novel targets for treatment of obesity-associated metabolic disease.


Surgical Endoscopy and Other Interventional Techniques | 2012

Consensus statement of the consortium for LESS cholecystectomy

Sharona S. Ross; Alexander A. Rosemurgy; Michael M. Albrink; Edward Choung; Giovanni Dapri; Scott S. Gallagher; Jonathan Hernandez; Santiago Horgan; William W. Kelley; Michael M. Kia; Jeffrey J. Marks; Jose J. Martinez; Yoav Mintz; Dmitry Oleynikov; Aurora A. Pryor; David D. Rattner; Homero Rivas; Kurt K. Roberts; Eugene Rubach; S. Schwaitzberg; Lee L. Swanstrom; John J. Sweeney; Erik Wilson; Harry Zemon; Natan Zundel

Many surgeons attempting Laparo-Endoscopic Single Site (LESS) cholecystectomy have found the operation difficult, which is inconsistent with our experience. This article is an attempt to promote a standardized approach that we feel surgeons with laparoscopic skills can perform safely and efficiently. This is a four-trocar approach consistent with the four incisions utilized in conventional laparoscopic cholecystectomy. After administration of general anesthesia, marcaine is injected at the umbilicus and a 12-mm vertical incision is made through the already existing anatomical scar of the umbilicus. A single four-trocar port is inserted. A 5-mm deflectable-tip laparoscope is placed through the trocar at the 8 o’clock position, a bariatric length rigid grasper is inserted through the trocar at the 4 o’clock position (to grasp the fundus), and a rigid bent grasper is placed through the 10-mm port (to grasp the infundibulum). This arrangement of the instruments promotes minimal internal and external instrument clashing with simultaneous optimization of the operative view. This orientation allows retraction of the gallbladder in a cephalad and lateral direction, development of a window between the gallbladder and the liver which promotes the “critical view” of the cystic duct and artery, and provides triangulation with excellent visualization of the operative field. The operation is concluded with diaphragmatic irrigation of marcaine solution to minimize postoperative pain. Standardization of LESS cholecystectomy will speed adoption, reduce intraoperative complications, and improve the efficiency and safety of the approach.


BMJ Innovations | 2017

Wearable technology in the operating room: a systematic review

Lauren Kolodzey; Peter Grantcharov; Homero Rivas; Marlies P. Schijven; Teodor P. Grantcharov

Wearable technology is an emerging manifestation of consumer electronics that has the potential to revolutionise healthcare. The novel hands-free design and clinically relevant functionalities of various wearable devices hold significant promise for surgery, but the breadth and quality of evidence supporting clinical implementation in the operating room remains unclear. The objective of this article is to provide an objective overview of the available literature regarding the use of wearable technology in surgery, both in clinical and simulated experimental settings. A systematic review examining the use of wearable technology in surgery was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines using the MEDLINE and Web of Science databases from inception through 15 January 2016. Three authors independently screened the titles and abstracts of the retrieved articles and those that satisfied the defined inclusion criteria were selected for a full-text review. A total of 87 publications were included in this review. These articles predominantly described the use of Google Glass, GoPro or customised head-mounted displays (HMDs) in a wide range of intraoperative clinical settings. The included articles were categorised based on the highlighted areas of clinical impact, with the majority (56) discussing various applications for enhancing intraoperative safety and efficiency. Almost all articles cited technological limitations and privacy concerns as serious barriers to the implementation of wearable technology in the operating room. Evidence in the available literature regarding the use of wearable technology in the operating room shows promise, but high-quality clinical trials are needed to fully understand their clinical impact. Further, it will be essential to address existing technological limitations, develop healthcare-specific applications, and integrate privacy-protecting safeguards before it may be feasible for wearable devices to seamlessly integrate into the operative environment.


American Journal of Obstetrics and Gynecology | 2017

Bowel Endometriosis: Diagnosis and Management

Camran Nezhat; A. Li; R.C. Falik; Daniel Copeland; Gity Meshkat Razavi; Alexandra Shakib; Catalina Mihailide; Holden Bamford; Lucia DiFrancesco; Salli I. Tazuke; Pejman Ghanouni; Homero Rivas; Azadeh Nezhat; Ceana Nezhat; Farr Nezhat

&NA; The most common location of extragenital endometriosis is the bowel. Medical treatment may not provide long‐term improvement in patients who are symptomatic, and consequently most of these patients may require surgical intervention. Over the past century, surgeons have continued to debate the optimal surgical approach to treating bowel endometriosis, weighing the risks against the benefits. In this expert review we will describe how the recommended surgical approach depends largely on the location of disease, in addition to size and depth of the lesion. For lesions approximately 5‐8 cm from the anal verge, we encourage conservative surgical management over resection to decrease the risk of short‐ and long‐term complications.


Annals of Surgery | 2018

Magnetic Surgery: Results from First Prospective Clinical Trial in 50 Patients.

Homero Rivas; Ignacio Robles; Francisco Riquelme; Marcelo Vivanco; Julio Jiménez; Boris Marinkovic; Mario Uribe

Objective: To evaluate a new magnetic surgical system during reduced-port laparoscopic cholecystectomy in a prospective, multicenter clinical trial. Background: Laparoscopic instrumentation coupled by magnetic fields may enhance surgeon performance by allowing for shaft-less retraction and mobilization. The movements can be performed under direct visualization, generating different angles of traction and reducing the number of trocars to perform the procedure. This may reduce well-known associated complications of trocars, including incisional pain, scarring, infection, bowel, and vascular injuries, among others. Methods: A prospective, multicenter, single-arm, open-label study was performed to assess the safety and performance of a magnetic surgical system (Levita Magnetics’ Surgical System). The investigational device was used during a 3-port laparoscopic technique. The primary endpoints evaluated were safety and feasibility of the device to adequately mobilize the gallbladder to achieve effective exposure of the targeted surgical site. Patients were followed for 30 days postprocedure. Results: Between January 2014 and March 2015, 50 patients presenting with benign gallbladder disease were recruited. Forty-five women and 5 men with an average age of 39 years (18–59), average body mass index of 27 kg/m2 (20.4–34.1) and an average abdominal wall thickness of 2.6 cm (1.8–4.6). The procedures were successfully performed in all 50 patients. No device-related serious adverse events were reported. Surgeons rated as “excellent” (90%) or “sufficient” (10%) the exposure of the surgical site. Conclusions: This clinical trial shows that this new magnetic surgical system is safe and effective in reduced-port laparoscopic cholecystectomy.


Asian Journal of Endoscopic Surgery | 2013

Present and future advanced laparoscopic surgery.

Homero Rivas; Daniela Díaz-Calderón

Modern laparoscopy, starting with Kurt Semms insufflators and the first successful appendectomies, has only been around for approximately 30 years. Since those early successes, the technology has grown from the inception of basic laparoscopy to endoscopic surgery through natural orifices, and it continues to evolve by leaps and bounds with computer‐assisted surgery and improved robotics in surgery. Without question, laparoscopy has revolutionized the way we perform standard surgery, especially relative to the techniques that had been used for hundreds of years. Despite the development of multiple novel technologies since the 1980s, very little has changed with regard to basic conceptualizations and practice of laparoscopy. In this review article, we will describe the highlights of recent advanced laparoscopic surgery procedures, their potential applications within the field of surgery, and how these advances may impact and improve future quality and patient outcomes.


PLOS ONE | 2017

Adipose tissue macrophages impair preadipocyte differentiation in humans

Li Fen Liu; Colleen M. Craig; Lorna L. Tolentino; Okmi Choi; John M. Morton; Homero Rivas; Samuel W. Cushman; Edgar G. Engleman; Tracey McLaughlin

Aim The physiologic mechanisms underlying the relationship between obesity and insulin resistance are not fully understood. Impaired adipocyte differentiation and localized inflammation characterize adipose tissue from obese, insulin-resistant humans. The directionality of this relationship is not known, however. The aim of the current study was to investigate whether adipose tissue inflammation is causally-related to impaired adipocyte differentiation. Methods Abdominal subcutaneous(SAT) and visceral(VAT) adipose tissue was obtained from 20 human participants undergoing bariatric surgery. Preadipocytes were isolated, and cultured in the presence or absence of CD14+ macrophages obtained from the same adipose tissue sample. Adipocyte differentiation was quantified after 14 days via immunofluorescence, Oil-Red O, and adipogenic gene expression. Cytokine secretion by mature adipocytes cultured with or without CD14+macrophages was quantified. Results Adipocyte differentiation was significantly lower in VAT than SAT by all measures (p<0.001). With macrophage removal, SAT preadipocyte differentiation increased significantly as measured by immunofluorescence and gene expression, whereas VAT preadipocyte differentiation was unchanged. Adipocyte-secreted proinflammatory cytokines were higher and adiponectin lower in media from VAT vs SAT: macrophage removal reduced inflammatory cytokine and increased adiponectin secretion from both SAT and VAT adipocytes. Differentiation of preadipocytes from SAT but not VAT correlated inversely with systemic insulin resistance. Conclusions The current results reveal that proinflammatory immune cells in human SAT are causally-related to impaired preadipocyte differentiation, which in turn is associated with systemic insulin resistance. In VAT, preadipocyte differentiation is poor even in the absence of tissue macrophages, pointing to inherent differences in fat storage potential between the two depots.


Annals of Surgery | 2014

Increasing access to specialty surgical care: application of a new resource allocation model to bariatric surgery.

Eric Leroux; John M. Morton; Homero Rivas

Objectives:To calculate the public health impact and economic benefit of using ancillary health care professionals for routine postoperative care. Background:The need for specialty surgical care far exceeds its supply, particularly in weight loss surgery. Bariatric surgery is cost-effective and the only effective long-term weight loss strategy for morbidly obese patients. Without clinically appropriate task shifting, surgeons, hospitals, and untreated patients incur a high opportunity cost. Methods:Visit schedules, time per visit, and revenues were obtained from bariatric centers of excellence. Case-specific surgeon fees were derived from published Current Procedural Terminology data. The novel Microsoft Excel model was allowed to run until a steady state was evident (status quo). This model was compared with one in which the surgeon participates in follow-up visits beyond 3 months only if there is a complication (task shifting). Changes in operative capacity and national quality-adjusted life years (QALYs) were calculated. Results:In the status quo model, per capita surgical volume capacity equilibrates at 7 surgical procedures per week, with 27% of the surgeons time dedicated to routine long-term follow-up visits. Task shifting increases operative capacity by 38%, resulting in 143,000 to 882,000 QALYs gained annually. Per surgeon, task shifting achieves an annual increase of 95 to 588 QALYs,

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Daniel J. Scott

University of Texas Southwestern Medical Center

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